1. Field of the Invention
The present invention relates to a screwdriver having a ratchet mechanism, in particular to a ratchet mechanism provided in a rear portion of a handle to change the turning direction of a tool sleeve and to replace a tool head accurately.
2. Description of the Prior Art
There are various ratchet hand tools on the market. Each has its special function, such as U.S. Pat. No. 5,875,693 which uses a gear to secure and to change the turning direction. The gear may get damaged easily, causing meshing inappropriately.
A ratchet mechanism for a screwdriver, such as U.S. Pat. Nos. 6,070,503, 6,253,654 and 6,854,363, is provided at a front portion or at a front end of a handle, which may accidentally touch an adjusting switch when operating the screwdriver.
In addition, a conventional screwdriver has the parts assembled in an axial direction, and is provided with a knob to change the direction. This design has a locating device to do the adjustment. The locating direction of the locating device is parallel to the assembled direction of the screwdriver. It is difficult to adjust the locating device.